Coating materials and methods for enhanced reliability

Abstract

Glass coating materials and methods are disclosed for the coating of glass substrates used in the manufacturer of photovoltaic solar modules such that the coating enhances the reliability of the module by reducing its susceptibility to potential induced degradation (PID). Coating materials are disclosed that reduce soiling on the front surface of the glass; that increase the surface resistivity of the glass and that repel moisture and that seal the surface from the ingress of moisture. Further electrically conductive coatings are disclosed that reduce the electric field between the front and back surfaces of the glass and hence reduce ion mobility within the glass and transport from the interior glass surface to the solar cell. There are additional configuration choices for fine tuning associated with separately optimizing the exterior and interior glass coating. Finally, coating processes and methods are disclosed for coating glass substrates with the disclosed materials.

What is claimed is: 
     
       1. A PID resistant photovoltaic solar module, comprising:
 a front cover-glass with a coating, wherein the coating includes a nanoparticle additive selected from the group consisting of SnO 2 , Al 2 O 3 , Si 3 N 4 , ZrO 2 , HfO 2  and Ce 2 O 3 ; 
 a first layer of encapsulant; 
 at least one photovoltaic solar cell; 
 a second layer of encapsulant; and 
 a back cover-sheet, 
 wherein the front cover-glass with the coating has an anti-reflective property, a hydrophobic property and an enhanced ion-migration blocking property when compared to the same front cover-glass without the coating; and 
 wherein the front cover-glass is coated on at least one surface selected from the surfaces consisting of: a front surface, a back surface, and at least one edge surface. 
 
     
     
       2. The solar module of  claim 1  wherein, the front cover-glass front-side coating has a refractive index and a thickness selected from the group consisting of: i) the refractive index between 1.52 and 1.25 and the thickness of between 50 nm and 250 nm; and ii) the refractive index between 1.52 and 1.45 and the thickness of between 50 nm and 10 μm. 
     
     
       3. The solar module of  claim 1  wherein a sheet resistance of the front cover-glass coating is less than 10 10 Ω/□ and at least the front and back surfaces of the front cover glass are coated and all coated surfaces are electrically connected. 
     
     
       4. The solar module of  claim 1  wherein a sheet resistance of the front cover-glass coating is higher than the sheet resistance of the equivalent front cover-glass that is uncoated. 
     
     
       5. The solar module of  claim 1  wherein the front cover-glass further has an oleophobic property. 
     
     
       6. The solar module of  claim 1 , wherein the coating comprises a coating composition of a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z  
 
 where R is independently methyl or optionally a substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1. 
 
     
     
       7. The solar module of  claim 6 , wherein the coating is prepared from at least two sols and wherein the at least two sols are separately hydrolyzed before preparing the coating. 
     
     
       8. The solar module of  claim 6 , wherein the front cover-glass is a pre-treated front cover glass before the coating is applied. 
     
     
       9. The solar module of  claim 8 , wherein the pre-treated front cover-glass is pretreated by a physical pretreatment or a chemical pretreatment before the coating is applied. 
     
     
       10. A PID resistant photovoltaic solar module, comprising:
 a front cover-glass with a coating, wherein the coating comprises at least one of conductive carbon nanotubes (CNT) or silver nanowires dispersed within the coating; 
 a first layer of encapsulant; 
 at least one photovoltaic solar cell; 
 a second layer of encapsulant; and 
 a back cover-sheet, 
 wherein the front cover-glass with the coating has an anti-reflective property, a hydrophobic property and an enhanced ion-migration blocking property when compared to the same front cover-glass without the coating; and 
 wherein the front cover-glass is coated on at least one surface selected from the surfaces consisting of: a front surface, a back surface, and at least one edge surface. 
 
     
     
       11. The solar module of  claim 10 , wherein the front cover-glass front-side coating has a refractive index and a thickness selected from the group consisting of: i) the refractive index between 1.52 and 1.25 and the thickness of between 50 nm and 250 nm; and ii) the refractive index between 1.52 and 1.45 and the thickness of between 50 nm and 10 μm. 
     
     
       12. The solar module of  claim 10 , wherein the coating comprises a coating composition of a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z  
 
 where R is independently methyl or optionally substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group, a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1. 
 
     
     
       13. The solar module of  claim 12 , wherein the coating is prepared from at least two sols and wherein the at least two sols are separately hydrolyzed before preparing the coating. 
     
     
       14. A method of manufacturing a PID resistant photovoltaic solar module by:
 (i) preparing a coating composition that contains a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z ,
 
 
 wherein the coating composition comprises at least one of conductive carbon nanotubes (CNT) or silver nanowires dispersed within the coating composition; 
 where R is independently methyl or optionally a substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group, a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1; 
 (ii) pretreating a sheet of cover-glass; 
 (ii) coating the sheet of cover-glass with the coating composition on at least one surface selected from a front, a back and at least one edge of the sheet of cover glass; 
 (iii) heating the sheet of cover-glass to cure the coating; and 
 (iv) assembling the photovoltaic solar module. 
 
     
     
       15. The method of  claim 14 , further comprising pretreating the sheet of cover glass by washing with water. 
     
     
       16. The method of  claim 14  wherein the sheet of cover-glass is coated by roll-coating. 
     
     
       17. The method of  claim 14  wherein, the sheet of cover-glass is heated by heating to a temperature between 100° C. and 500° C. 
     
     
       18. The method of  claim 14 , wherein the step of preparing further comprises separately hydrolyzing at least two of the sols before preparing the combination coating. 
     
     
       19. The method of  claim 14 , further comprising pretreating the front cover glass by a physical pretreatment or a chemical pretreatment before the coating is applied. 
     
     
       20. The method of  claim 14 , further comprising disposing a layer of encapsulant on a photovoltaic solar cell of the photovoltaic solar module. 
     
     
       21. A method of manufacturing a PID resistant photovoltaic solar module by:
 (i) preparing a coating composition that contains a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z ;
 
 
 where R is independently methyl or optionally a substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group, a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1; 
 (ii) pretreating a sheet of cover-glass; 
 (ii) coating the sheet of cover-glass with the coating composition on at least one surface selected from a front, a back and at least one edge of the sheet of cover glass; 
 (iii) heating the sheet of cover-glass to cure the coating; and 
 (iv) assembling the photovoltaic solar module; 
 wherein the coating composition comprises at least one additive selected from the group consisting of SnO 2 , Al 2 O 3 , ZrO 2 , Si 3 N 4 , HfO 2  and Ce 2 O 3 , wherein a sheet resistance of the sheet of cover glass is reduced when compared to an uncoated sheet resistance of a sheet of cover glass, wherein the additive is in the form of nanoparticles. 
 
     
     
       22. A PID resistant photovoltaic solar module, comprising:
 a front cover-glass with a coating, wherein the coating comprises at least one of conductive carbon nanotubes (CNT) or silver nanowires dispersed within the coating composition, the coating comprising a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z  
 
 
 where R is independently methyl or optionally substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group, a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1; 
 at least one photovoltaic solar cell with at least one layer of encapsulant disposed on a surface of the photovoltaic solar cell; and 
 a back cover-sheet, 
 wherein the front cover-glass with the coating has an anti-reflective property, a hydrophobic property and an enhanced ion-migration blocking property when compared to the same front cover-glass without the coating; and 
 wherein the front cover-glass is coated on at least one surface selected from the surfaces consisting of: a front surface, a back surface, and at least one edge surface. 
 
     
     
       23. The solar module of  claim 22 , the coating further comprising an additive selected from the group consisting of SnO 2 , Al 2 O 3 , ZrO 2 , HfO 2 , Si 3 N 4 , and Ce 2 O 3 , wherein a sheet resistance of the front cover glass is reduced when compared to an uncoated sheet resistance of the front cover glass. 
     
     
       24. The solar module of  claim 22 , wherein the at least one layer of encapsulant comprises two layers of encapsulant. 
     
     
       25. A PID resistant photovoltaic solar module, comprising:
 a front cover-glass with a coating, the coating comprising a nanoparticle additive comprising a metallic oxide, nitride or carbide, and the coating further comprising a combination of sols having a formula:
   RSi(OH) 2 O 0.5 ] a [RSiO 1.5 ] b [RSi(OH)O] c [R′Si(OH) 2 O 0.5 ] m [R′SiO 1.5 ] n [R′Si(OH)O] p [SiO 2 ] w [Si(OH)O 1.5 ] x [Si(OH) 2 O] y [Si(OH) 3 O 0.5 ] z  
 
 
 where R is independently methyl or optionally a substituted or unsubstituted C2 to C10 alkyl group, a substituted or unsubstituted C3 to C20 cycloalkyl group, a substituted or unsubstituted C1 to C10 hydroxyalkyl group, a substituted or unsubstituted C6 to C20 aryl group, a substituted or unsubstituted C2 to C20 heteroaryl group, a substituted or unsubstituted C2 to C10 alkenyl group, a substituted or unsubstituted carboxyl group, a substituted or unsubstituted (meth)acryl group, a substituted or unsubstituted glycidylether group, or a combination thereof; 
 where R′ is a fluorine substituted C3 alkyl group or optionally C4 to C10 alkyl group, a fluorine substituted C3 to C20 cycloalkyl group, a fluorine substituted C1 to C10 hydroxyalkyl group, a fluorine substituted aryl group, a fluorine substituted C2 to C20 heteroaryl group, a fluorine substituted C2 to C10 alkenyl group, a fluorine substituted carboxyl group, a fluorine substituted (meth)acryl group, a fluorine substituted glycidylether group, or a combination thereof; and 0<a,b,c,w,x,y,z<0.9, 0≦m,n,p<0.9, and a+b+c+m+n+p+w+x+y+z=1; 
 at least one photovoltaic solar cell with at least one layer of encapsulant disposed on a surface of the photovoltaic solar cell; and 
 a back cover-sheet, 
 wherein the front cover-glass with the coating has an anti-reflective property, a hydrophobic property and an enhanced ion-migration blocking property when compared to the same front cover-glass without the coating; 
 wherein the front cover-glass is coated on at least one surface selected from the surfaces consisting of: a front surface, a back surface, and at least one edge surface. 
 
     
     
       26. The solar module of  claim 25 , the coating further comprising an additive selected from the group consisting of SnO 2 , Al 2 O 3 , ZrO 2 , HfO 2 , Si 3 N 4 , and Ce 2 O 3 , wherein a sheet resistance of the front cover glass is reduced when compared to an uncoated sheet resistance of the front cover glass. 
     
     
       27. The solar module of  claim 26 , wherein the additive is in the form of nanoparticles.